1. Field of the Invention
The present invention relates to a lens module and an eye fundus camera, particularly to a compact handheld lens module and an eye fundus camera using the same.
2. Description of the Prior Art
In an eye fundus observation device, light is guided to the eye fundus of a testee, and then the eye fundus is imaged on the eye of the tester or a photosensor of a camera (such as a film or an image sensor of the camera). The conventional eye fundus observation devices include the direct ophthalmoscope, the indirect ophthalmoscope and the eye fundus camera. Different from the direct ophthalmoscope, the indirect ophthalmoscope forms an intermediary image of the eye fundus in advance and then projects the intermediary image onto the eye of the tester or the photosensor of a camera. The eye fundus camera captures and records the images of the eye fundus of a testee, and the image records are convenient to store and transfer.
The conventional eye fundus observation deices respectively have their disadvantages. For example, the direct ophthalmoscope has an observation angle of merely about 5 degrees and thus can only observe the optic disc or the fovea centralis. Besides, the user of the direct ophthalmoscope must be very close to the testee. The indirect ophthalmoscope has a wider observation field and can also observe the ocular capillaries in addition to the optic disc and the fovea centralis. However, the user of the indirect ophthalmoscope still has to approach the testee very closely. Further, neither the direct ophthalmoscope nor the indirect ophthalmoscope can record the image of the eye fundus of the testee. The eye fundus camera has a wider observation field and a capability of observing and recording the eye fundus of the testee and exempts the tester from closely approaching the testee. However, the eye fundus camera is bulky, hard to carry about and unlikely to apply to some special testees, such as infants, bedridden patients or handicapped patients. Neither the current handheld ophthalmoscope nor the current handheld eye fundus camera provides a precision light beam to guide the testee to accurately adjust the angle of his eyeball for shooting different regions of the eye fundus. Although the desktop eye fundus camera provides a precision light beam, it occupies considerable space.
Accordingly, the manufacturers are eager to develop an eye fundus observation device not only having the abovementioned advantages but also having reduced volume.